The invention relates to hand-held screwdrivers having interchangeable blades which are held within the handle and are available to be selected for various types of screws such as those having a straight slot, Phillips head, etc. Alternatively, the blades can be adapted to receive sockets or other shapes to hold or drive various types of fasteners.
There are and have been on the market multiblade screwdrivers which are simply units with a hollow handle in which a number of screw driver blades are stored, and with a removable cap so that the blades can be removed and affixed to one end of the handle in operative position. These have the negative factor of loose blades which can be readily removed and misplaced.
Other forms of multiblade screw drivers are illustrated by U.S. Pat. Nos. 4,463,788; 4,716,796; 4,557,943 and 5,228,363. All of these have multiple, usually six, screwdriver blades or shafts which are mounted in multiple peripheral openings or storage slots disposed lengthwise on the outer portion of the handle. The operator can select the desired blade located in the storage portion of the handle and slide it forward toward an operative position. The blade moves forward through the storage slot to the forward end of the handle until it reaches a point where a stopping mechanism on the base of the blade engages the inside of the cap and prevents the blade from falling out. The blade is then in the outer portion of a cross slot in the cap perpendicular to and above the storage slot. It can be moved in the cross slot toward the center of the handle and when in the center, moved toward the back of the handle into a chuck element, generally having a magnet in its base, which holds the blade in operative position on the central axis of the screwdriver assembly. Shaped portions in the base of the blade engage correspondingly shaped portions of the chuck to prevent rotation of the blade when it is in the chuck. This permits a downward, twisting force to be exerted on the blade/handle combination to engage the fastener and prevent rotation of the blade in the handle to permit screwing or unscrewing of the fastener.
In the prior art devices, the cross slot through which the blade moves from storage to operative position in the chuck is composed of two parts, a slot in the top of the cap which encloses the forward end of the handle and a corresponding slotted portion in a rotatable disk which can rotate within the cap. When moving the blade from storage to operative position, the cross slots are lined up to permit the movement of the selected blade from the storage to the operative position or vice versa. To retain the blade in the chuck and prevent movement of the blade either outward or within the slot, the disk is rotated, perhaps 90 degrees, so that the disk having the slot no longer is lined up with the slot in the cap and thus the blade is held or locked in place in the chuck.
It is an object of the invention to prevent rotation of the cap assembly when the blade is in the chuck, thus precluding the introduction of a second blade into the cross-slot which can occur in prior art devices because a user""s hands gripping the handle and twisting the screwdriver can fairly easily rotate and unlock the exposed lock ring on the disk mounted in the forward end of the handle.
It is a further object of the invention to construct a multiblade screwdriver with the use of fewer and simpler parts while providing the same ability to move from storage to operative position, to retain the blade within the handle and to move to the operative position, locking the blade into the operative position.
Applicant""s improved construction provides for a blade of simple polygonal, and preferably hexagonal, cross sectional configuration, eliminating relatively expensive forming or machining steps required to make the blade configuration in the prior art devices. Thus, the blade configuration can be formed from a hexagonal length of steel or like metal having a screwdriver shape or configuration at the outer end. The portion near the inner end has a flat notch cut in opposite sides of the hex, preferably in angled portions. This notch is cut across the hex on two portions of the hex opposite each other to form a flat sided notch which will enable the blade to slide along a track portion of the opening which is formed in the cap. A lug or xe2x80x9cwingxe2x80x9d is formed on the inside base portion of the blade adjacent one or both of the flat notched portions for the purpose of engaging the inside of the cap adjacent to the hex opening track portions to prevent the blade from being removed from the handle.